This working paper gives an overview of the three main datasets of the EU Transaction Log (EUTL): the datasets of Operator Holdings Accounts (OHAs), Person Holding Accounts (PHAs), and the EUTL Transfer dataset. It describes in detail how these datasets can be linked, expanded, and analyzed. Particular attention is given to the different possibilities of relating EU ETS accounts to the parent companies and to classifying transactions by establishing different categories. Different options for adding allowance prices to the EUTL Transfer dataset are presented based on analysis of potential forward and futures contracts. The technical descriptions are intended to serve as a background against which to use the EUTL Transfer dataset for future research. A set of guidelines is proposed for researchers intending to employ the datasets in their own analyses.